Solve Using the Quadratic Formula -4x^2-7x+2=0

$- 4 x^{2} - 7 x + 2 = 0$

Step 1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 2

Substitute the values $a = - 4$ , $b = - 7$ , and $c = 2$ into the quadratic formula and solve for $x$ .

$\frac{7 \pm \sqrt{{(- 7)}^{2} - 4 \cdot (- 4 \cdot 2)}}{2 \cdot - 4}$

Step 3

Simplify.

Simplify the numerator.

Raise $- 7$ to the power of $2$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot - 4 \cdot 2}}{2 \cdot - 4}$

Multiply $- 4 \cdot - 4 \cdot 2$ .

Multiply $- 4$ by $- 4$ .

$x = \frac{7 \pm \sqrt{49 + 16 \cdot 2}}{2 \cdot - 4}$

Multiply $16$ by $2$ .

$x = \frac{7 \pm \sqrt{49 + 32}}{2 \cdot - 4}$

Add $49$ and $32$ .

$x = \frac{7 \pm \sqrt{81}}{2 \cdot - 4}$

Rewrite $81$ as $9^{2}$ .

$x = \frac{7 \pm \sqrt{9^{2}}}{2 \cdot - 4}$

Pull terms out from under the radical, assuming positive real numbers.

$x = \frac{7 \pm 9}{2 \cdot - 4}$

Multiply $2$ by $- 4$ .

$x = \frac{7 \pm 9}{- 8}$

Move the negative in front of the fraction.

$x = - \frac{7 \pm 9}{8}$

Step 4

The final answer is the combination of both solutions.

$x = - 2, \frac{1}{4}$